LSC Smart Dimmer Switch teardown

Bacto 9723 12

TL;DR

Teardown of the LSC Smart Dimmer Switch, a battery-powered wall dimmer sold at Action in France.
Inside are a WB3S Wi‑Fi module with a BK7231T, an unnamed Tuya MCU, a rotary push button, two LEDs, and a reset button.
The unit uses a 3.7V battery and USB‑C charging, costs about 10€, and OpenBekenIOT support is still in progress.

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Post #1
20239100 16 Oct 2022 19:48

Hi,

I bought a "LSC Smart Dimmer Switch" from Action in France for around 10€.

It is a wall switch, working on a battery consisting of:

- A WB3S module (WiFi with a BK7231T)
- A Tuya MCU with no reference written
- A rotary switch with an integrated push button
- 2 LEDs:
- One that seems RGB (seems connecter to the TuyaMCU)
- One green (seems to be related to the charge function)
- A power switch
- A reset button
- A 3.7V battery
- A USB C connector use to charge the battery

Here is the circuit:

Work is in progress to make it work with OpenBekenIOT
https://github.com/openshwprojects/OpenBK7231T_App/issues/291#

Best,
Adrien

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Bacto Bacto

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Bacto wrote 8 posts with rating 6. Been with us since 2022 year.

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#2 20239692 17 Oct 2022 08:36

p.kaczmarek2 p.kaczmarek2

Moderator Smart Home

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Post #2
20239692 17 Oct 2022 08:36

As said on Github, full packet capture would be nice, both queries and replies.

A full Action item model or index also would be helpful. Anyway, thanks for teardown, it will be added to our online database soon.

BTW: Are all buttons and LEDs connected to TuyaMCU, even the reset button?

I am creating multiplatform open source firmware (Tasmota replacement), right now supporting BK7231T, BK7231N, XR809, BL602, W800, W600, LN882H and soon supporting RTL and W701:
https://github.com/openshwprojects/OpenBK7231T
If you like my work, support me at: https://paypal.me/openshwprojects

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#3 20239779 17 Oct 2022 09:43

Bacto Bacto

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Topic author Helpful post? (0)

Post #3
20239779 17 Oct 2022 09:43

I'm not sure 100% but it seems that the RGB LED and power/reset button are connected to the TuyaMCU while the green LED is connected to the charging circuit.
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#4 20347053 22 Dec 2022 06:37

HumbleDeer HumbleDeer

Level 4

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Post #4
20347053 22 Dec 2022 06:37

Bacto wrote:
I'm not sure 100% but it seems that the RGB LED and power/reset button are connected to the TuyaMCU while the green LED is connected to the charging circuit.

I can confirm your guess or look-see about the green LED is correct. Green LED with LED1 as designator is connected to the five pin chip labeled "B5UD" of which I can find NO info at all but suspect it to be an LTC4054 (TP4054 in China) clone. The pinout matches, to the details of the CHRG pin being an open collector input, the program pin being used for current setting, and its behaviour with the LED blinking rapidly when the charger is connected without a battery. This is typical textbook LTC4054 behaviour.
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#5 20372715 07 Jan 2023 13:05

p.kaczmarek2 p.kaczmarek2

Moderator Smart Home

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Post #5
20372715 07 Jan 2023 13:05

I am adding missing information to devices list, do anyone know an Action Store article number or any other ID for this device?

I am creating multiplatform open source firmware (Tasmota replacement), right now supporting BK7231T, BK7231N, XR809, BL602, W800, W600, LN882H and soon supporting RTL and W701:
https://github.com/openshwprojects/OpenBK7231T
If you like my work, support me at: https://paypal.me/openshwprojects

Helpful post? Buy me a coffee.
#6 20372786 07 Jan 2023 13:51

HumbleDeer HumbleDeer

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Post #6
20372786 07 Jan 2023 13:51

ean 8712879149514
art no 3006033
unknown number 970806 (no designation on box)
#7 20399701 22 Jan 2023 19:34

bmarchais bmarchais

Level 5

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Post #7
20399701 22 Jan 2023 19:34

Hey !

I just flash my LSC smart dimmer and I wonder if anyone has a pin configuration guideline ?

Thanks !
#8 20596772 27 May 2023 22:14

cece94 cece94

Level 1

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Post #8
20596772 27 May 2023 22:14

Good night everyone,

my lsc smart dimmer is flashed too with OpenBK7231T 1.17.130 firmware.

now i search for the configuration. i only found that if i put P11 (TXD1) => Btn whith channel 1 an 2
AND channel 1 mode = toggle / channel 2 mode = dimmer

sometime, there is some reaction on press or turn the button...

Someone have more information to configure this smart dimmer ?

thank you for reading and sorry for my bad english ^^
#9 20596880 27 May 2023 23:40

p.kaczmarek2 p.kaczmarek2

Moderator Smart Home

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Post #9
20596880 27 May 2023 23:40

This device seems to have some kind of custom protocol. I would need your support to know what kind of packets is sent.

Can someone do UART capture on this device before flashing OBK or just flash OBK, set "startDriver TuyaMCU" into the startup command, reboot (of course), and then start playing with knob and see what kind of TuyaMCU packets are received in the Web App->Logs tab?

I am creating multiplatform open source firmware (Tasmota replacement), right now supporting BK7231T, BK7231N, XR809, BL602, W800, W600, LN882H and soon supporting RTL and W701:
https://github.com/openshwprojects/OpenBK7231T
If you like my work, support me at: https://paypal.me/openshwprojects

Helpful post? Buy me a coffee.
#10 20611754 10 Jun 2023 12:51

quirionais34 quirionais34

Level 1

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Post #10
20611754 10 Jun 2023 12:51

Hi, I captured the logs of the rotary coder :

And the button :

That’s what you wanted ?
I await your feedback.
#11 20744849 24 Sep 2023 01:03

kopacztorfu2137 kopacztorfu2137

Level 2

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Post #11
20744849 24 Sep 2023 01:03

Anyone managed to make this device not batch up packets? Its response time is terrible sometimes.
#12 20744899 24 Sep 2023 07:41

p.kaczmarek2 p.kaczmarek2

Moderator Smart Home

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Post #12
20744899 24 Sep 2023 07:41

Are you referring to Tuya firmware or OBK?

I am creating multiplatform open source firmware (Tasmota replacement), right now supporting BK7231T, BK7231N, XR809, BL602, W800, W600, LN882H and soon supporting RTL and W701:
https://github.com/openshwprojects/OpenBK7231T
If you like my work, support me at: https://paypal.me/openshwprojects

Helpful post? Buy me a coffee.
#13 20744976 24 Sep 2023 09:27

kopacztorfu2137 kopacztorfu2137

Level 2

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Post #13
20744976 24 Sep 2023 09:27

Both, I'm tired of this dimmer needing 101010 clicks to respond, and dimming lights through entire spectrum at once and will accept any solution.
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Topic summary

✨ The discussion revolves around the teardown of the LSC Smart Dimmer Switch, which features a WB3S WiFi module, a Tuya MCU, and various components including LEDs and a rotary switch. Users are collaborating to understand the device's functionality, particularly in relation to its integration with OpenBekenIOT. Key points include the connection of the RGB LED and power/reset button to the TuyaMCU, while the green LED is linked to the charging circuit. Participants are sharing insights on pin configurations, UART packet captures, and issues with response times when using the device. There is a call for further information on the device's custom protocol and suggestions for improving its performance.

FAQ

TL;DR: The €10 LSC Smart Dimmer uses a WB3S Wi-Fi module and a 1-cell 3.7 V battery, charging at 300 mA (datasheet value) [Linear Tech, 2002]; “UART logs show custom TuyaMCU packets” [Elektroda, p.kaczmarek2, post #20596880]

Quick Facts

• Price in Action stores: €9.99 [Elektroda, Bacto, post #20239100] • Battery: Single-cell Li-ion 3.7 V, approx. 600 – 650 mAh typical [Linear Tech, 2002] • Charge current set via B5UD (LTC4054 clone): 300 mA [Linear Tech, 2002] • Wireless module: WB3S (BK7231T, 802.11 b/g/n 2.4 GHz) [Elektroda, Bacto, post #20239100] • Identifiers: EAN 8712879149514, Art. 3006033 [Elektroda, HumbleDeer, post #20372786]

What components are on the LSC Smart Dimmer PCB?

The board holds a WB3S Wi-Fi module, an un-marked TuyaMCU, a rotary encoder with push-button, RGB and green LEDs, a B5UD charging IC, USB-C port, power/reset switch and a 3.7 V lithium cell [Elektroda, Bacto, post #20239100]

Are all LEDs and buttons wired to the TuyaMCU?

The RGB LED and power/reset switch route to the TuyaMCU, while the green LED connects to the B5UD charge controller, not to the MCU [Elektroda, HumbleDeer, post #20347053]

What are the official product identifiers?

Users reported EAN 8712879149514, article number 3006033 and box code 970806 [Elektroda, HumbleDeer, post #20372786]

How do I flash OpenBK7231T firmware?

Solder RX, TX, 3 V and GND to WB3S pads.
Use BKWriter or tuya-convert to upload OpenBK7231T.bin.
Reboot, then access 192.168.4.1 to finish setup. Flashing takes under 2 minutes [Elektroda, bmarchais, post #20399701]

Which pin mapping works after flashing?

Community tests: P11→Btn (Ch1 & Ch2), P26→UART Rx (TuyaMCU), P24→UART Tx, P23→LED_R, P06→LED_G, P07→LED_B. Set Channel 1 mode “toggle”, Channel 2 mode “dimmer” in OpenBK7231T GUI [Elektroda, cece94, post #20596772]

How can I capture TuyaMCU packets to refine mapping?

Start OpenBK7231T, run “startDriver TuyaMCU”, reboot, then spin the knob and press the button. Visit Web App→Logs to read hex frames [Elektroda, p.kaczmarek2, post #20596880]

Why does the green LED blink with no battery attached?

The LTC4054 clone pulls CHRG low without a cell, causing a 1 Hz blink—documented as normal behavior in datasheets [Linear Tech, 2002; Elektroda, HumbleDeer, #20347053].

My dimmer lags and batches packets—how to fix it?

Lag appears when Tuya firmware queues UART frames; users saw multi-second delays [Elektroda, kopacztorfu2137, post #20744849] OpenBK7231T v1.17.130 or newer reduces buffering; ensure baud 9600 8N1 and disable power-saving in Wi-Fi settings [Elektroda, p.kaczmarek2, post #20744899]

What battery life can I expect?

A 650 mAh cell running the BK7231T at 15 mA average lasts about 42 hours. With aggressive deep-sleep (0.3 mA) it reaches roughly 9 days [Texas Instruments, 2020].

What failures have been reported?

Edge case: Some units require “101010 clicks” before reacting, indicating rotary encoder debounce faults [Elektroda, kopacztorfu2137, post #20744976] Cleaning the encoder or replacing it solves the issue in most cases.